Thursday, October 17, 2013
Mechanical and Civil Engineering Seminar
Estimating Collapse Vulnerability of Buildings in Earthquakes using a Butterworth Filter
Song Shiyan, Dr., Department of Mechanical and Civil Engineering, Caltech
We develop an efficient collapse prediction model, the PFA (Peak Filtered Acceleration) model, for buildings subjected to different types of ground motions.
To predict whether a building will collapse in response to a given ground motion, we first extract long-period components from the ground motion using a Butterworth low-pass filter with suggested order and cutoff frequency. The order depends on the type of ground motion, and the cutoff frequency depends on the building`s natural frequency and ductility. We then compare the filtered acceleration time history with the capacity of the building. The capacity of the building is a constant for 2-dimentional buildings and a limit domain for 3-dimentional buildings. If the filtered acceleration exceeds the building's capacity, the building is predicted to collapse. Otherwise, it is expected to survive the ground motion.
The PFA collapse prediction model greatly reduces computational complexity while archiving good accuracy. Based on the developed collapse prediction model, we propose to use PFA (Peak Filtered Acceleration) as a new ground motion intensity measure for collapse prediction.